Localization of MCC (mutated in colorectal cancer) in various tissues of mice and its involvement in cell differentiation

Localization of the MCC (mutated in colorectal cancer) gene product, a cell cycle-regulating protein mutated in several colorectal tumors, in various mouse tissues was examined by immunohistochemistry and immunoelectron micro scopy. MCC was localized on microvilli and in the apical cytoplasm in renal proximal tubule epithelial cells and pancreatic acinar cells. In hepatocyt es, MCC was exclusively detected on microvilli. MCC was highly expressed in the cerebral cortex and the molecular layer of the cerebellar cortex and w as partially associated with membrane organelles in neuronal elements. Adre nal chromaffin cells showed little expression of MCC, MCC was localized to the cell margins of ependymal cells, thyroid follicular cells, and anterior pituitary cells. In parotid acinar cells, only the apical surface was immu nopositive. MCC was not expressed in skeletal and cardiac muscle. MCC was p resent at lateral cell borders in the duodenum and colon epithelium. In add ition, the apical cytoplasm of colon epithelial cells exhibited intense imm unoreactivity. The amount of MCC increased during differentiation of NGF-tr eated PC12 cells. In conclusion, MCC was expressed in differentiated cells and was associated with the plasma membrane and membrane organelles. In add ition to the negative regulation of the cell cycle, MCC may be involved in cell differentiation.